Está is used for location and condition.. Many people here quote 'no matter how you feel (emotions, feelings, temporary characteristics) and where you are (location) - that is when you use estár'
it is catchy in my opinion ;)

Just to help clarify, "es" is the he/she/you (formal) conjugation of the verb "ser". Which does mean "to be". However it is used for things that don't change. For example, "he is a boy" would be "él es un niño".

Estar is the verb "to be" for things that do change. Like in this question, "the taxi is here" so it would be "el taxi está aquí". It MUST have the accent in order for it to be the verb form.

Este/esta mean "this"

If you need more clarification then try reading the comments every time one of these comes up. There's a lot of helpful information.